There are known commercial aircrafts (CBA vector 123, SARA, AVANTI, 7J7) powered with propeller engines located in the rear part of the aircraft supported by the fuselage by means of pylons.
One of the problems raised by this aircraft configuration is related to failure events such as a PBR (“Propeller Blade Release”) event, i.e. an event where a blade of one of the propeller engines comes off and hits the fuselage, an UERF (“Uncontained Engine Rotor Failure”) event, i.e. an event where a part of the rotor of the engine breaks, it is released and hits the fuselage, an ice shedding event where ice shedding created in the tips of the blades can be thrown at high speed over the fuselage, or any other “Large Damage” event.
The design of said rear fuselage shall therefore take into account such events and guarantee its capability for maintaining stability and proceed to a safe landing, i.e. shall be an impact resistant and damage tolerant fuselage.
As a consequence of the failure in the engine, one of the blades of the propeller engine or any other engine component can be detached and impact against the rear fuselage at high speed, sectioning it. In this emergency condition, the aircraft operates with only one engine generating a forward thrust outside the plane of symmetry of the airplane. This thrust causes a yawing moment which must be balanced with a side aerodynamic force caused by the vertical tail plane of the empennage, so that the aircraft can continue navigating stably. As the vertical tail plane is located above the rear fuselage, this side aerodynamic force generates a torsion along the rear fuselage. If the blade impacts against the fuselage and sections it, the torsional strength of the fuselage is considerably reduced because the torsional rigidity of a closed section is proportional to the total area enclosed by the section, whereas the torsional rigidity of an open section is proportional to the material area of the section.
Propeller engines may also be in the wing such that the detachment of a propeller blade can impact the central fuselage in front of the wing. In this area of the fuselage, the torsion that the mentioned fuselage must support is relatively low, and do not involve a critical emergency condition. However, this condition changes when the propeller engines are located at the rear part of the aircraft in front of the empennage, because then the torque generated by the empennage due to the failure of an engine is very high and can cause a catastrophic situation for the aircraft which must be prevented.
As it is well known, weight is a fundamental aspect in the aeronautic industry and therefore there is a current trends to use composite material instead metallic material even for primary structures.
The composite materials that are most used in the aeronautical industry consist of fibers or fiber bundles embedded in a matrix of thermosetting or thermoplastic resin, in the form of a preimpregnated or “prepreg” material. Its main advantages refer to:                Their high specific strength with respect to metallic materials. It is the strength/weight equation.        Their excellent behavior under fatigue loads.        The possibilities of structural optimization thanks to the anisotropy of the material and the possibility of combining fibers with different orientations, allowing the design of the elements with different mechanical properties adjusted to the different needs in terms of applied loads.        
WO 2009/068638 discloses an impact resistant fuselage made with composite materials comprising an outer skin and an inner skin, both skins being joined by means of radial elements configuring then a multi-cell structure providing the required torsional strength in the rear part of said aircrafts.
The present invention is also addressed to attend the aeronautical industry demand related to rear fuselages subjected to said failure events and propose a different solution than WO 2009/068638.